*{
    margin: 0;
    padding:0;
    box-sizing: border-box;
}
a{
    text-decoration: none;
}
.box{
    width:300px;
    margin: 100px auto;
}
li{
    list-style: none;
   display: inline-block;
}

.box .nav > li{
    list-style: none;
    display: inline-block;
    position: relative;
    cursor: pointer;
}
.box .main li a{
    font-size: 13px;
    color: #000;
}
.box .main .active-1 a{
    color: orange;
}
.box .nav > .active::after{
    content: '';
    border-bottom: 3px solid orange;
    position: absolute;
    width:100%;
    left:0;
    bottom:-3px;
}
.box .main div{
    display: none;
}
.box .main > .active{
    display: block;
}